A radial ball bearing 40 as of the prior art is shown in FIG. 21 and is generally used as a ball bearing for bearing various miniature devices. This radial ball bearing 40 comprises an inner race 41, balls 42 and an outer race 43 and employs a so-called double sealing structure wherein sealing members 44 are arranged respectively on both sides of the balls 42 provided between the outer race 43 and inner race 41 in order to prevent dust and the like from entering the ball part and reducing the performance during the use.
In assembling the above structures, first of all, the inner race 41 and outer race 43 are put into a jig, then the outer race 43 or inner race 41 is slid into a position such as to make a clearance into which the balls 42 can be inserted, a proper number of balls 42 are put into the clearance and are moved to a predetermined position, the outer race 43 and inner race 41 are made coaxial with each other, a retainer is put in, is positioned in the hole and is pressed in and then the sealing members 44 are appropriately fitted to assemble the radial ball bearing 40.
In fitting the bearing to a fitting member 45, a fitting screw 46 which is a separate member is inserted into the inner race 41 and is screwed into a threaded part 45a of the fitting member 45 and side of the fitting member 45 is thus fixed so that side of the outer race 43 may be rotatable or, as shown in FIG. 22, a fixing member 47 is fitted and fixed to the outer race 43 so that the side may be fitting member 45 side is rotatable.
However, there are defeciencies in that the radial ball bearing 40 of the above mentioned construction is difficult to assemble, is therefore high in the cost, requires the fitting screw 46 in order to be fitted to the fitting member 45, and is therefore difficult to fit.